1. Field of the Invention
This invention relates to satellite positioning systems. In particular, this invention relates to satellite positioning systems implemented using the processing power of a host in layered communication with tracker hardware.
2. Related Art
Worldwide use of satellite positioning systems (SPS), such as the Global Positioning System (GPS) is growing at a rapid pace. Current trends are calling for the incorporation of GPS services into a broad range of electronic devices and systems, including Personal Digital Assistants (PDAs), cellular telephones, portable computers, automobiles, and the like. At the same time, manufacturers constantly strive to reduce costs, simply designs and produce the most cost-attractive product possible for consumers.
In the past, providing a GPS solution, such as handheld GPS devices, often required expensive dedicated GPS signal reception and processing hardware, as well as dedicated post processing hardware for resolving location measurements, displaying location coordinates, updating map displays, and the like. However, given the rapid growth in speed, sophistication, and processing power of the host microprocessors present in the host computer devices (e.g., in a cell phone, personal digital assistant or automobile), the possibility exists for allowing the host computer to bear the burden not only of running its regular applications, but also to operate as part of the GPS solution. Such an approach is presented in U.S. Pat. No. 6,430,503, titled “Distributed GPS Navigation System”, the entirety of which is incorporated herein by reference in its entirety.
Currently, however, there is a strong push toward incorporating GPS solutions in many electronic devices designed by numerous manufacturers. Of course, each device varies considerably in architecture, operating system, hardware interfaces, and the like. Prior GPS solutions did not provide the flexibility that allowed the solutions to be adapted to a wide range of electronic devices. Instead, expensive customized solutions were needed for each device, thereby undesirably increasing costs and delaying the introduction of GPS services into a wide range of devices. The prior GPS host solutions also rely on interrupts to the host computer in order to service a GPS function. The use of interrupts adversely impacts the performance of the host computer.
Known GPS solutions are often developed or customized for specific devices and applications. Such customization increases the complexity of implementing GPS systems on numerous platforms and operating systems. Further, known GPS systems are often not able to take advantage of changes in software and hardware without changing a large portion of the software in a GPS device. The customized or specific device design approach also limits the ability to create application program interfaces that can be marketed and delivered separate from the GPS hardware.
Therefore, a need exists for implementations of GPS solutions that overcome the problems noted above and others previously experienced.